Edison

The technology of Natural Gas Combined-Cycle Power Plants

The combined cycle is fed by natural gas (or CCGT, Combined Cycle Gas Turbines) and is the most efficient and eco-friendly technology of thermoelectricity generation available today. 

This technology offers two big advantages over traditional ones:
• high yield (55-56% as opposed to less than 40%)
• reduced environmental impact (through use of methane instead coal or oil)
• lower cost of energy produced

The combined-cycle plants are made up of:

   • Gas turbine (GT), where combustion of natural gas takes place. The expansion of gas products rotates a first turbine and then the first electric generator connected to it.  

   • Steam generator , where the steam from the gas turbine is used to produce high pressure steam.

   • Steam turbine (TV), in which steam produced by the recycled-steam generator expands, rotating another turbine and then a second electric generator, with production of additional electricity.

   • Condenser, in which the exhausted steam from the steam turbine is condensed using air from the outside. 


In practice, starting from a certain volume of fuel, electricity is produced with two systems: the gas cycle and the steam cycle, thereby optimising the use of the initial energy resource.

Water is not used for the steam condensation or machinery cooling: being located in an area that historically has little water, the plant has been equipped with special facilities (air exchangers and condensers) that allow for an almost complete saving of the water resource.

The exhaust gases are also channelled into the atmosphere through a dedicated chimney and are constantly monitored.

The following chart compares the emissions of a conventional plant, fed by oil fuel (multiplied by 100), with a combined-cycle one (expressed as relative percentages).